A PHS Grant Application has been submitted to the National Library of Medicine for subvention of publication of the book, Postnatal Development of the Rat Skull. In Part 1 of the book, the cranium and mandible of the rat are demonstrated by drawings and photographs at successive postnatal ages. In Part 2, development of the cranium and mandible are demonstrated by alizarin vital staining and photographs of sections. This combination of methods affords comprehensive demonstration of the development of individual bones, of skeletal composites and of the skull as a whole.